CA1278958C - Sea anchor - Google Patents
Sea anchorInfo
- Publication number
- CA1278958C CA1278958C CA000509065A CA509065A CA1278958C CA 1278958 C CA1278958 C CA 1278958C CA 000509065 A CA000509065 A CA 000509065A CA 509065 A CA509065 A CA 509065A CA 1278958 C CA1278958 C CA 1278958C
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- base
- truncated
- strength member
- cone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
- B63B21/24—Anchors
- B63B21/48—Sea-anchors; Drogues
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
- B63B39/06—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water
- B63B2039/067—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water effecting motion dampening by means of fixed or movable resistance bodies, e.g. by bilge keels
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
- Piles And Underground Anchors (AREA)
- Valve-Gear Or Valve Arrangements (AREA)
- Valve Device For Special Equipments (AREA)
- Earth Drilling (AREA)
Abstract
ABSTRACT OF DISCLOSURE
A sea anchor for a vessel, which is formed in a generally symmetrical configuration of a hollow and baseless truncated cone or paraboloid with a wide mouth member at the edge of the cone base of strong material forming a hollow generally truncated cone which is attached to a wide mouth strength member and in which the strong material has orifices in it so as to cause energy dissipation by the increased velocity therethrough and with the area of the orificial opening being not greater than 75 percent of the projected surface area of the truncated cone and where the depth of truncated cone is such that the ratio of the diameter of the base of the cone to the height or depth is in the range of 80 to 90 percent. The sea anchor of the invention has a bridal means attached to the wide mouth strength member arranged to have members meet at the longi-tudinal centerline of the cone for joining to a single anchor line from said vessel. The joining point the distance from the base of the cone in the range of 1.8 to 2 times the diameter of the strength member at the base.
A sea anchor for a vessel, which is formed in a generally symmetrical configuration of a hollow and baseless truncated cone or paraboloid with a wide mouth member at the edge of the cone base of strong material forming a hollow generally truncated cone which is attached to a wide mouth strength member and in which the strong material has orifices in it so as to cause energy dissipation by the increased velocity therethrough and with the area of the orificial opening being not greater than 75 percent of the projected surface area of the truncated cone and where the depth of truncated cone is such that the ratio of the diameter of the base of the cone to the height or depth is in the range of 80 to 90 percent. The sea anchor of the invention has a bridal means attached to the wide mouth strength member arranged to have members meet at the longi-tudinal centerline of the cone for joining to a single anchor line from said vessel. The joining point the distance from the base of the cone in the range of 1.8 to 2 times the diameter of the strength member at the base.
Description
l ~ ~7~5~3 1 S l 6 ¦ This invention relates to a class of devices which are used 71 by vessels at sea to slow the drift of a vessel and to hold it 81 into a desired attitude to the wind and sea that occurs when i~
9¦ encounters a gale, i.e., wind having speed in excess of 40 knots~
10¦ Such devices for defining the invention herein could be generally 11 ¦ called floating resistance bodies and include drogues that are 12 ¦ streamed over the stern of a vessel and sea anchors which are 13 ¦ streamed over the bow of the vessel.
14 ¦ PRIOR ART
15 ¦ It has been known to use various kinds of devices as floating 16 ¦ resistance bodies that are tethered to a vessel and used in the 17 ¦ circumstances where gale force winds blow across the sea to 18 ¦ increase the wave motion and to increase the pressure on the 19 vessel. The pressure on the vessel by high wind, when added the waves rolling under it, can cause it~to broach or have its hull 21 lie broadside to the waves. This constitutes a dangerous 22 condition, for a breaking wave top can cause the vessel to roll 23 over. As an additional hazard in these gale conditions, the 24 vessel can be zaused to move`at high speed relative ~o the water and that high speed may drive it quickly towards land and endanger 26 it. Such high speed can also result in instability of control 27 with the possibility of the vessel turning over. Because of 28 these conditions, seamen over many years were using either drogues 29 or sea anchors, the primary purpose of which is to orient the 3~
$~
9¦ encounters a gale, i.e., wind having speed in excess of 40 knots~
10¦ Such devices for defining the invention herein could be generally 11 ¦ called floating resistance bodies and include drogues that are 12 ¦ streamed over the stern of a vessel and sea anchors which are 13 ¦ streamed over the bow of the vessel.
14 ¦ PRIOR ART
15 ¦ It has been known to use various kinds of devices as floating 16 ¦ resistance bodies that are tethered to a vessel and used in the 17 ¦ circumstances where gale force winds blow across the sea to 18 ¦ increase the wave motion and to increase the pressure on the 19 vessel. The pressure on the vessel by high wind, when added the waves rolling under it, can cause it~to broach or have its hull 21 lie broadside to the waves. This constitutes a dangerous 22 condition, for a breaking wave top can cause the vessel to roll 23 over. As an additional hazard in these gale conditions, the 24 vessel can be zaused to move`at high speed relative ~o the water and that high speed may drive it quickly towards land and endanger 26 it. Such high speed can also result in instability of control 27 with the possibility of the vessel turning over. Because of 28 these conditions, seamen over many years were using either drogues 29 or sea anchors, the primary purpose of which is to orient the 3~
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2 0f l4 1 ¦vessel so that the narrow dimension of the bow and stern i9 2 ¦presented to the wave and the wind so as to cause the least vessel 3 ¦motion and pressure thereon to allow the vessel ~o ride out the 4 Istorm.
5 ¦ When a sea anchor is streamed over the bow so that the head 6 ¦of the vessel faces the oncoming wind and the wave~, and when a 7 ¦arogue is streamed over the stern so that the end of the vessel 8 ¦faces the wind and the waves, the selection of which resistance 9 ¦body should be used depends upon the sea and navigation conditions 10 ¦characteristic of the vessel, and in addition, characteristics of 11 ¦the resistance body.
12 ¦ A sea anchor has been generally in the form of a hollow cone, 13 Ithe open face of the cone being pulled by straps or ropes to the 14 ¦ oncoming water so that the resistance of the device to movement in 15 ¦ the water is ~ caused by the large projected area of the open 16 ¦ mouth base of the cone. The bridal means of the device is 17 ¦ attached to a line going up to the vessel. At the apex of the 18 ¦ cone, there may be a small hole therein and a line attached to lg ¦ that apex so that the vessel can attach a trip line to it and 20 ¦ collapse the cone. The cone is made~of a heavy canvas material to 21 ¦ withstand strong pressures and may have a float atta~hed to it to 22 maintain it a certain depth below the surface of the water. Sea 23 anchors are always streamed over the bow of the vessel that seeks 24 to use it and are generally thought to be of a very high resistance so as to minimize the drift of the vessel through the 26 water.
27 ~..~ r variant of the sea anchor is a very strong paracnute 28 ¦where the bridal means comes down to a single point and then 29 ¦attach a line to the vessel. This device also has a trip line and 31 ¦ a float.
3 0~ 14 ~ ~ ~ 78 ~
1¦ Another type of sea anchor is one in which the device is 21 formed in the shape of a pyramid and the open base is cross-braced 3 ¦ with some kind of strength member so as to maintain its shape as 4¦ it is being pulled through the water, and function~ much the same 51 as a conical or parachute type.
6¦ These sea anchors all have a recognized disadvantage in that 71 they have a high resistance to being pulled through the water, so 8 ¦that when the vessel rises towards the top of a wave and is hit by 9¦ the blast of high velocity air, a sudden force is caused to move 10¦ the vessel ~ackward relative to the water and the force is then 11 ¦ passed along the line to the sea anchor. It can be extremely 12 ¦ large and can cause damage by breaking the line, breaking the 3 ¦ point of attachment to the vessel, or breaking the anchor itself.
L4 Moreover, as the resistance to movement is constant and strong, the force that is imposed upon the line of the vessel can be 16 extremely large and result in damage. Also, due to the high force 17 characteristics, these devices are often marked with a caution not 18 to use in hurricane-force winds. Thus when a device is really 19 needed, it becomes too dangerous to use.
Other seamen, when faced with gale conditions, prefer to use 21 a resistance body as a drogue which is streamed over the stern of 22 the vessel. In prior known devices, it can consist of things as 23 simple as a mass of sails and/or spars all wrapped together. It 24 has also been known for fishermen to-take their large fishing nets and ~ling them over the stern so as to keep the stern to the 26 breaking seas. Such drogues are uncertain of performance and have 27 been known to be uneven due to sllrfacing and, at times, have been 29 thrown on board the vessel by breaking seas.
4 of 14 1 ~78~3~,8 `
1 ¦ THE PRESENT INVENTION
3 ¦ - This in~ention is based on the in~ight that a resistance body 4 ¦ needed to slow the vessel's drift should have an initial high 5 ¦ resistance, but the resistance ~hould not be so high or last so 6 ¦ long that it causes excessive strain on either the tethered line 7 ¦ or the vessel itself. And further, that after the initial surge 8 ¦ of the vessel is transmitted to the device, it should be a~le to 9 ¦ relieve that initial high strain on the line while continuing to 10 ¦create high resistance and thus dissipate the energy that is being 11 ¦placed upon the vessel by the wind and the sea. In particular, it 12 ¦is a concept here that by making the sea anchor with orifices 13 ¦ therein in the sides of the device that when it is caused to be 14 ¦ dragged through the water at higher velocity, the fluid passing 15 ¦ through the orifice will have its velocity increased relative to 16 ¦ the velocity of water entering the sea anchor, and as energy 17 ¦ dissipation under such conditions is a function of velocity to the 18 ¦ second power, the faster the sea anchor goes through the water, I the greater will be the energy dissipated by the orifices.
27 ~..~ r variant of the sea anchor is a very strong paracnute 28 ¦where the bridal means comes down to a single point and then 29 ¦attach a line to the vessel. This device also has a trip line and 31 ¦ a float.
3 0~ 14 ~ ~ ~ 78 ~
1¦ Another type of sea anchor is one in which the device is 21 formed in the shape of a pyramid and the open base is cross-braced 3 ¦ with some kind of strength member so as to maintain its shape as 4¦ it is being pulled through the water, and function~ much the same 51 as a conical or parachute type.
6¦ These sea anchors all have a recognized disadvantage in that 71 they have a high resistance to being pulled through the water, so 8 ¦that when the vessel rises towards the top of a wave and is hit by 9¦ the blast of high velocity air, a sudden force is caused to move 10¦ the vessel ~ackward relative to the water and the force is then 11 ¦ passed along the line to the sea anchor. It can be extremely 12 ¦ large and can cause damage by breaking the line, breaking the 3 ¦ point of attachment to the vessel, or breaking the anchor itself.
L4 Moreover, as the resistance to movement is constant and strong, the force that is imposed upon the line of the vessel can be 16 extremely large and result in damage. Also, due to the high force 17 characteristics, these devices are often marked with a caution not 18 to use in hurricane-force winds. Thus when a device is really 19 needed, it becomes too dangerous to use.
Other seamen, when faced with gale conditions, prefer to use 21 a resistance body as a drogue which is streamed over the stern of 22 the vessel. In prior known devices, it can consist of things as 23 simple as a mass of sails and/or spars all wrapped together. It 24 has also been known for fishermen to-take their large fishing nets and ~ling them over the stern so as to keep the stern to the 26 breaking seas. Such drogues are uncertain of performance and have 27 been known to be uneven due to sllrfacing and, at times, have been 29 thrown on board the vessel by breaking seas.
4 of 14 1 ~78~3~,8 `
1 ¦ THE PRESENT INVENTION
3 ¦ - This in~ention is based on the in~ight that a resistance body 4 ¦ needed to slow the vessel's drift should have an initial high 5 ¦ resistance, but the resistance ~hould not be so high or last so 6 ¦ long that it causes excessive strain on either the tethered line 7 ¦ or the vessel itself. And further, that after the initial surge 8 ¦ of the vessel is transmitted to the device, it should be a~le to 9 ¦ relieve that initial high strain on the line while continuing to 10 ¦create high resistance and thus dissipate the energy that is being 11 ¦placed upon the vessel by the wind and the sea. In particular, it 12 ¦is a concept here that by making the sea anchor with orifices 13 ¦ therein in the sides of the device that when it is caused to be 14 ¦ dragged through the water at higher velocity, the fluid passing 15 ¦ through the orifice will have its velocity increased relative to 16 ¦ the velocity of water entering the sea anchor, and as energy 17 ¦ dissipation under such conditions is a function of velocity to the 18 ¦ second power, the faster the sea anchor goes through the water, I the greater will be the energy dissipated by the orifices.
20 ¦ The new invention is a sea anch~r for a vessel, which is 21 ¦ formed in a generally ~ymmetrical configuration of a hollow and 22 ¦ baseless truncated cone or paraboloid with a wide mouth member at 23 ¦ the edge of the cone base of strong material forming a hollow 24 generally truncated cone which is attached to a wide mouth strength member and in which the strong material has orifices in 26 it so as to cause energy dissipation by the increased velocity 27 ~nerethrough and with the area of the orificial opening being not 28 greater than 75 percent of the projected surface area of the 29 truncated cone and where the depth of truncated cone is such that the ratio of the diameter of the base of the cone *o the height or 32 depth i5 in the range of 80 to 90 percent. The sea anchor of the 5 o~ 14 il :`~
I ~.~78~3 1 ¦invention has a bridal means attached to the wide mouth ~trength 2 ¦member arranged to have members meet at the longitudinal-center-3 ¦line of the cone for joining to a single anchor line from said 4 ¦vessel. The joining point the distance from the base of the cone 5 ¦in the range of 1.8 to 2 times the diameter of the strength member 6 1at the base.
7 ¦ The invention also contemplates that the sea anchor will have 8 la high initial resistance to movement and good longitudinal 9 ¦stability due to the fact that the truncated end of the sea anchor 10 ¦has an imperforate end and such imperforate area, as compared to 11 ¦the area of the open base of said truncated cone, will be in the 2 ¦range of 15 to 25 percent of such projected base area.
3 ¦ A further aspect of the invention is that the aforesaid sea 4 ¦anchor will be of different sizes depending on the displacement of l5 ¦ the vessel to which it is to be attached. The size will be one 16 ¦ (1) cubic foot of sea anchor for each 2600 pounds of displacement.
17 ¦ More particularly, a sea anchor of the type described will 18 ¦ have a multiplicity of circumferentially uniformly spaced 1~ ¦ longit~dinal strength webs attached to and extending between the 20 ¦ open base strength member and the imperforate member. It will 21 ¦ al~o have a number of substantially uniformly spaced longitudin-22 ¦ ally spaced webs arranged transverse to said longitudinal webs to 23 ¦ form therewith a grid so that the orificial openings therein are 24 ¦ generally rectangular.
I ~.~78~3 1 ¦invention has a bridal means attached to the wide mouth ~trength 2 ¦member arranged to have members meet at the longitudinal-center-3 ¦line of the cone for joining to a single anchor line from said 4 ¦vessel. The joining point the distance from the base of the cone 5 ¦in the range of 1.8 to 2 times the diameter of the strength member 6 1at the base.
7 ¦ The invention also contemplates that the sea anchor will have 8 la high initial resistance to movement and good longitudinal 9 ¦stability due to the fact that the truncated end of the sea anchor 10 ¦has an imperforate end and such imperforate area, as compared to 11 ¦the area of the open base of said truncated cone, will be in the 2 ¦range of 15 to 25 percent of such projected base area.
3 ¦ A further aspect of the invention is that the aforesaid sea 4 ¦anchor will be of different sizes depending on the displacement of l5 ¦ the vessel to which it is to be attached. The size will be one 16 ¦ (1) cubic foot of sea anchor for each 2600 pounds of displacement.
17 ¦ More particularly, a sea anchor of the type described will 18 ¦ have a multiplicity of circumferentially uniformly spaced 1~ ¦ longit~dinal strength webs attached to and extending between the 20 ¦ open base strength member and the imperforate member. It will 21 ¦ al~o have a number of substantially uniformly spaced longitudin-22 ¦ ally spaced webs arranged transverse to said longitudinal webs to 23 ¦ form therewith a grid so that the orificial openings therein are 24 ¦ generally rectangular.
25 ¦ The improved sea anchor gains its characteristics from a 26 ¦ unique combination of multiple orifice velocity increase and high 27 ¦ drag coefficient form.
281 .
I 6 0f 14 ~ 78~58 . _ , 2 ¦ In order for those skilled in the art to understand--how to 3 ¦make and use the invention, there is set forth hereinafter a 4 ¦detailed description of the preferred ~mbodimen~ of the invention~
5 ¦which is merely exemplary. In the Figures:
6 1 FIG. 1 is a side view of the sea anchor; and 7 ¦ FIG. 2 is an end ~iew of the sea anchor to illustra~e its 8 ¦details of construction.
9 ¦ A resistance body for attachment to a vessel for use in 10 ¦gale-force conditions and above, is ill~trated in the Figures in 11 ¦which the sea anchor 10, chown as attached to an anchor rode 12 by 12 la swivel fitting 14, in turn is attached to bridal means 26 at a 13 ¦ point identified in FIG. 1 as 30. Thus the invention is shown in 14 ¦ the mode in which it i~ tethered to vessel needing same by the 15 ¦ anchor rode 12 and is arranged so that in looking at FIG. 1, it 16 ¦ would move through the water relative right to left.
17 ¦ The sea anchor of the invention as illustrated in FIG. 1, is 18 1 a three dimensional body having the general shape of a truncated 19 ¦ cone but it could be more precisely discribed as a three-20 ¦ dimensional body of rotation of a parabola, i.e. a paraboloid.
21 ¦ The "truncated cone" term will be nsed to encompass all of the 22 shapes of hollow thxee-dimensional bodies in which the base has a 23 larger major diameter or dimension than the peak or top part o~
24 the body, with the outer surface slanting inwardly from the base at an acute angle. It is contemplated by the invention here that 26 the imaginary surface of the sea anchor runs in a generally longi-~/ ~dinal direction and shall also be generally slanted inwardly 28 terminating at an impeforate truncated end as shown in FIG.l as pl6c~
A ~ 18. This 4~3 is termed the second ~trength member 18 at one end of the sea anchor is arranged so that it is imperforate, it is of 31 such a size that its cross gectional area projected to larger area 7 of 14 ~ ~ 7~
of the cone base and to the water entering the sea anchor, and is in the range oE 15 to 25 percent of such area. The purpose of this imperforate section is to provide a large resistance area to the straight line water flow entering the sea anchor, and, secondly, to have a high-strength section to which the construction described hereinafter can be applied in a strong manner.
As shown, the wide mouth strength member 16 is in the form of a circle, preferably would be a ring or a flexible cable, covered by a strong cloth member. Accordingly, the strength member is generally of a uniform weight throughout its perimeter so the weight distribution is symmetrical. Running between the large open mouth member 16 and the imperforate strength member 18 is a large number of longitudinal webs 20 arranged so that they are attached to both of those members at circumferentially uniformly spaced positions. A number of substantially uniformly spaced longitudinally spaced webs 22 are arranged transverse to the longitudinal webs so that when attached thereto they form a grid with rectangular orificial opening 24 that are uniformly distributed throughout the side of the sea anchor as shown. In arranging such webs or straps their broad faces lie in the plane of the surface of the cone and transverse to the flow water. Of course, as the sea anchor illustrated is to be deployed, it has attached to the large strength member 16 a bridal 26 consisting of a number of straps or ropes which come to a common point at 30, in which there is fixed a ring 32 for attachment to the swivel 14.
A specific embodiment of a sea anchor made in accordance with the present invention has the base strength member or ring 16, that is forty one inches in diameter, a diameter of the second strength member 18, being eighteen inches with the longitudinal length of the sea anchor being forty eight inches. The longitudinal members, webs 20, and the transverse or circumferential webs 22 are made from two inch wide webbing of the type that is used in construction and have a load carrying ability of approximately ~ of 1 s~
1 1 000 pound~. The horizontal webs 22 are sp~ced from each other 2 by about eight inches, except for the one that is closest to the 3 ring 18 and that is spaced nine inches thereform. The longitu~
4 dinal members 20 are spaced from each other so that they are on nine inch centers. The bottom strength member 18 consists of 6 three layers of nine ounce high strength cloth, with the ends of 7 the webs held therebetween and firmly attached by sewing. The 8 upper ends of the longitudinal webs 20 are held by a cloth that is 9 wrapped around the strength member 18 and over the ends of the webs and securely sewn thereto with a grommet 34 passed throughO
11 The grommets allow ropes or webs 28 to be passed around the 12 strength member 16 and securely fastened to itself. As 13 illustrated, there are seven rope legs, with a rope length of 14 seventy seven inches after securing. Each of those ropes are arranged so that they passed from the grommet on one side of the 16 sea anchor to the other side, and pass then through the ring 32.
17 When they have all been pacsed therethrough, then there is a 18 seizing that they are all held tightly together by small lines.
19 The strength member 16 which lies at the base of the truncated cone in the model specifically described has as its 21 basic strength member 3/8 x 1 x 19 layed cable, the ends of which 22 are fastened to each other by a butting-type of sleeve that is 23 pressed thereon in a manner known in the art.
24 A sea anchor made in accordance with the invention as specifically set forth hereinabove, was streamed to the stern of a A` 26 vessel having a displacement of about 25~tons, during a storm in 27 the Gulf Stream wherein the wind was blowing at force 10 and 28 generating very confused and steep seas. The result was the 29 ves~el changed rom one which was running before the sea with no sail~ on its mast at speeds that ranged from 3 knots on the back ~ ~ r l A
5~ ;
l¦s de of the wave to lO knot~ when the vessel went down the front 2 ¦of the wave. The vessel was so uncontrollable that as the wave 3 ¦rolled under it it would catch it and roll the vessel such that 4 ¦the rail went under water -- in other words, it was impo~sible to 5 ¦control the vessel. ~owever, after the sea anchor of ~he present 6 ¦invention was streamed over the stern, there was no strong sudden 7 ¦surge or high load on the anchor line and the speed of the vessel 8 ¦very quickly was reduced to approximately 3 knots under which 9 ¦conditions the vessel answered its helm, it stayed upright and the 10 ¦helmsman found that he could steer the vessel within a 90-degree 11 ¦quadrant. ~he sea anchor did not come out of the water, and it 12 ¦maintained a constant drag on the vessel.
L3 ¦ The sea anchor configuration as shown in FIG. 1 is 14 ¦ characterized by the fact that it is stable, that is, it will 15 ¦ maintain its constant relative position to the sea as it is 16 ¦ dragged through the water, and thus has a continued resistance 17 ¦ through the water to hold the vessel to which it is attached, in a 18 1 proper attitude to the sea and the wind. Because of the large 19 ¦ projected area of the ~ or apex of the sea anchor compared to 20 1 its open mouth, it has a high initial resistance to sudden 2~ impositions of pulling on the line, such that the resistance to 22 movement is very high when there is a sudden pull by the ship on 23 the line, but as soon as the device starts moving, the water 24 starts flowing through the orifices 24 thereof and the resistance drops. Then as the large body of water is broken up into many 26 streams that are accelerated through each of these orifices as the 27 vessel gains speea, the water is accelerated to a higher velocity 28 than when entering the orifice, yielding an energy loss that is 29 proportional to the square of the velocity change, plus the fact 31 that the surface-to-volume relationship of the water passing 10 of 14 ~ ~ 7~3~
therethrough is increased so that the skin friction portion of energy loss on the actual body of the sea anchor is increased over an e~uivalent imperforate cone of the same dimension.
It is believed that the stability of the sea anchor is maintained when the area of the strength member 18 has an area that is 15 to 25 percent of the projected area of the open ring 16. In addition to contributing to stability as the sea anchor is dragged through the water, the diameter of the rin~ 16 should be in the range of 80 to 90 percent of the height or depth of the truncated cone.
An additional benefit of the particular form and material of the improved sea anchor is extreme stability, so much so that it is most appropriate for retrieving a person from the water and bringing him aboard. A second person can even be prepositioned in the sea anchor to assist in the rescue of a disabled man overboard.
The imperforate areas or truncated end 18 of the cone may have a single high strength attachment point or opening to attach a line for additional control during man overboard rescue operation.
The resistive power of the device is a function of its size.
There are different sizes of sea anchors for different displacement of vessels and there is shown hereinbelow a Table I
which depicts the vital dimensions of sea anchors made according to the present invention in terms of the diameter of the ring 18 to the depth of the sea anchor, projected face area of the inside of the diameter of the strength member 16, the outer surface areas, and the volume contained within the truncated cone, all as related to ship displacement.
11 of 14 ~,:
~ ~,7~395~
TAsLE I
Diameter Projected Surface Ship & DepthArea Area Volume Displmt.
24 x 283.14 ft.26.42 ft.23.89 ft.310,200 lbs.
281 .
I 6 0f 14 ~ 78~58 . _ , 2 ¦ In order for those skilled in the art to understand--how to 3 ¦make and use the invention, there is set forth hereinafter a 4 ¦detailed description of the preferred ~mbodimen~ of the invention~
5 ¦which is merely exemplary. In the Figures:
6 1 FIG. 1 is a side view of the sea anchor; and 7 ¦ FIG. 2 is an end ~iew of the sea anchor to illustra~e its 8 ¦details of construction.
9 ¦ A resistance body for attachment to a vessel for use in 10 ¦gale-force conditions and above, is ill~trated in the Figures in 11 ¦which the sea anchor 10, chown as attached to an anchor rode 12 by 12 la swivel fitting 14, in turn is attached to bridal means 26 at a 13 ¦ point identified in FIG. 1 as 30. Thus the invention is shown in 14 ¦ the mode in which it i~ tethered to vessel needing same by the 15 ¦ anchor rode 12 and is arranged so that in looking at FIG. 1, it 16 ¦ would move through the water relative right to left.
17 ¦ The sea anchor of the invention as illustrated in FIG. 1, is 18 1 a three dimensional body having the general shape of a truncated 19 ¦ cone but it could be more precisely discribed as a three-20 ¦ dimensional body of rotation of a parabola, i.e. a paraboloid.
21 ¦ The "truncated cone" term will be nsed to encompass all of the 22 shapes of hollow thxee-dimensional bodies in which the base has a 23 larger major diameter or dimension than the peak or top part o~
24 the body, with the outer surface slanting inwardly from the base at an acute angle. It is contemplated by the invention here that 26 the imaginary surface of the sea anchor runs in a generally longi-~/ ~dinal direction and shall also be generally slanted inwardly 28 terminating at an impeforate truncated end as shown in FIG.l as pl6c~
A ~ 18. This 4~3 is termed the second ~trength member 18 at one end of the sea anchor is arranged so that it is imperforate, it is of 31 such a size that its cross gectional area projected to larger area 7 of 14 ~ ~ 7~
of the cone base and to the water entering the sea anchor, and is in the range oE 15 to 25 percent of such area. The purpose of this imperforate section is to provide a large resistance area to the straight line water flow entering the sea anchor, and, secondly, to have a high-strength section to which the construction described hereinafter can be applied in a strong manner.
As shown, the wide mouth strength member 16 is in the form of a circle, preferably would be a ring or a flexible cable, covered by a strong cloth member. Accordingly, the strength member is generally of a uniform weight throughout its perimeter so the weight distribution is symmetrical. Running between the large open mouth member 16 and the imperforate strength member 18 is a large number of longitudinal webs 20 arranged so that they are attached to both of those members at circumferentially uniformly spaced positions. A number of substantially uniformly spaced longitudinally spaced webs 22 are arranged transverse to the longitudinal webs so that when attached thereto they form a grid with rectangular orificial opening 24 that are uniformly distributed throughout the side of the sea anchor as shown. In arranging such webs or straps their broad faces lie in the plane of the surface of the cone and transverse to the flow water. Of course, as the sea anchor illustrated is to be deployed, it has attached to the large strength member 16 a bridal 26 consisting of a number of straps or ropes which come to a common point at 30, in which there is fixed a ring 32 for attachment to the swivel 14.
A specific embodiment of a sea anchor made in accordance with the present invention has the base strength member or ring 16, that is forty one inches in diameter, a diameter of the second strength member 18, being eighteen inches with the longitudinal length of the sea anchor being forty eight inches. The longitudinal members, webs 20, and the transverse or circumferential webs 22 are made from two inch wide webbing of the type that is used in construction and have a load carrying ability of approximately ~ of 1 s~
1 1 000 pound~. The horizontal webs 22 are sp~ced from each other 2 by about eight inches, except for the one that is closest to the 3 ring 18 and that is spaced nine inches thereform. The longitu~
4 dinal members 20 are spaced from each other so that they are on nine inch centers. The bottom strength member 18 consists of 6 three layers of nine ounce high strength cloth, with the ends of 7 the webs held therebetween and firmly attached by sewing. The 8 upper ends of the longitudinal webs 20 are held by a cloth that is 9 wrapped around the strength member 18 and over the ends of the webs and securely sewn thereto with a grommet 34 passed throughO
11 The grommets allow ropes or webs 28 to be passed around the 12 strength member 16 and securely fastened to itself. As 13 illustrated, there are seven rope legs, with a rope length of 14 seventy seven inches after securing. Each of those ropes are arranged so that they passed from the grommet on one side of the 16 sea anchor to the other side, and pass then through the ring 32.
17 When they have all been pacsed therethrough, then there is a 18 seizing that they are all held tightly together by small lines.
19 The strength member 16 which lies at the base of the truncated cone in the model specifically described has as its 21 basic strength member 3/8 x 1 x 19 layed cable, the ends of which 22 are fastened to each other by a butting-type of sleeve that is 23 pressed thereon in a manner known in the art.
24 A sea anchor made in accordance with the invention as specifically set forth hereinabove, was streamed to the stern of a A` 26 vessel having a displacement of about 25~tons, during a storm in 27 the Gulf Stream wherein the wind was blowing at force 10 and 28 generating very confused and steep seas. The result was the 29 ves~el changed rom one which was running before the sea with no sail~ on its mast at speeds that ranged from 3 knots on the back ~ ~ r l A
5~ ;
l¦s de of the wave to lO knot~ when the vessel went down the front 2 ¦of the wave. The vessel was so uncontrollable that as the wave 3 ¦rolled under it it would catch it and roll the vessel such that 4 ¦the rail went under water -- in other words, it was impo~sible to 5 ¦control the vessel. ~owever, after the sea anchor of ~he present 6 ¦invention was streamed over the stern, there was no strong sudden 7 ¦surge or high load on the anchor line and the speed of the vessel 8 ¦very quickly was reduced to approximately 3 knots under which 9 ¦conditions the vessel answered its helm, it stayed upright and the 10 ¦helmsman found that he could steer the vessel within a 90-degree 11 ¦quadrant. ~he sea anchor did not come out of the water, and it 12 ¦maintained a constant drag on the vessel.
L3 ¦ The sea anchor configuration as shown in FIG. 1 is 14 ¦ characterized by the fact that it is stable, that is, it will 15 ¦ maintain its constant relative position to the sea as it is 16 ¦ dragged through the water, and thus has a continued resistance 17 ¦ through the water to hold the vessel to which it is attached, in a 18 1 proper attitude to the sea and the wind. Because of the large 19 ¦ projected area of the ~ or apex of the sea anchor compared to 20 1 its open mouth, it has a high initial resistance to sudden 2~ impositions of pulling on the line, such that the resistance to 22 movement is very high when there is a sudden pull by the ship on 23 the line, but as soon as the device starts moving, the water 24 starts flowing through the orifices 24 thereof and the resistance drops. Then as the large body of water is broken up into many 26 streams that are accelerated through each of these orifices as the 27 vessel gains speea, the water is accelerated to a higher velocity 28 than when entering the orifice, yielding an energy loss that is 29 proportional to the square of the velocity change, plus the fact 31 that the surface-to-volume relationship of the water passing 10 of 14 ~ ~ 7~3~
therethrough is increased so that the skin friction portion of energy loss on the actual body of the sea anchor is increased over an e~uivalent imperforate cone of the same dimension.
It is believed that the stability of the sea anchor is maintained when the area of the strength member 18 has an area that is 15 to 25 percent of the projected area of the open ring 16. In addition to contributing to stability as the sea anchor is dragged through the water, the diameter of the rin~ 16 should be in the range of 80 to 90 percent of the height or depth of the truncated cone.
An additional benefit of the particular form and material of the improved sea anchor is extreme stability, so much so that it is most appropriate for retrieving a person from the water and bringing him aboard. A second person can even be prepositioned in the sea anchor to assist in the rescue of a disabled man overboard.
The imperforate areas or truncated end 18 of the cone may have a single high strength attachment point or opening to attach a line for additional control during man overboard rescue operation.
The resistive power of the device is a function of its size.
There are different sizes of sea anchors for different displacement of vessels and there is shown hereinbelow a Table I
which depicts the vital dimensions of sea anchors made according to the present invention in terms of the diameter of the ring 18 to the depth of the sea anchor, projected face area of the inside of the diameter of the strength member 16, the outer surface areas, and the volume contained within the truncated cone, all as related to ship displacement.
11 of 14 ~,:
~ ~,7~395~
TAsLE I
Diameter Projected Surface Ship & DepthArea Area Volume Displmt.
24 x 283.14 ft.26.42 ft.23.89 ft.310,200 lbs.
30 x 354.91 ft.29.16 ft.27.55 ft.319,800 lbs.
36 x 427.07 ft.212.9 ft.212.98 ft.334,100 lbs.
41 x 489.17 ft.216.12 ft.219.03 ft.350,000 lbs.
48 x S612.57 ft.221.80 ft.230.59 ft.380,300 lbs.
54 x 6315.90 ft.227.08 ft.243.18 ft.3113,500 lbs.
60 x 7019.63 ft.234.06 ft.259.56 ft.3156,500 lbs.
72 x 8428.27 ft.249.96 ft.2102.70 ft.3269,800 lbs.
It can be seen that the ratio of the ship displacement to the sea anchor volume shows that for every 2600 pounds oE
displacement there would be needed approximately 1 cubic foot of volume oE the sea anchor with the configuration of the oriEicial opening in the sea anchor being proportionally increased as described above.
The advantage of this particular type of sea anchor over any prior models is the concurrence of two special characteristics; a very low resistance to acceleration and a very high resistance to high speed while maintaining its hydraulic stability. The result is a very controlled low speed in which the controlled vessel is subject to the least strain from the wind, waves or the sea anchor itself.
Although the sea anchor has been described as being made up from straps, it should be borne in mind that the invention contemplates that orifices can be placed and controllably sized in the side of the surEace of the truncated cone oE the improved sea anchor as is desired for the sea conditions and vessel intended. Thus, other means of construction may be used to obtain the orifices between the strong surface sections of the sea anchor without departing from the spirit of the invention.
Moreover, it will be evident to those skilled in the art that changes in details of construction without departing from the principles of the invention.
12 of 14 `~,
36 x 427.07 ft.212.9 ft.212.98 ft.334,100 lbs.
41 x 489.17 ft.216.12 ft.219.03 ft.350,000 lbs.
48 x S612.57 ft.221.80 ft.230.59 ft.380,300 lbs.
54 x 6315.90 ft.227.08 ft.243.18 ft.3113,500 lbs.
60 x 7019.63 ft.234.06 ft.259.56 ft.3156,500 lbs.
72 x 8428.27 ft.249.96 ft.2102.70 ft.3269,800 lbs.
It can be seen that the ratio of the ship displacement to the sea anchor volume shows that for every 2600 pounds oE
displacement there would be needed approximately 1 cubic foot of volume oE the sea anchor with the configuration of the oriEicial opening in the sea anchor being proportionally increased as described above.
The advantage of this particular type of sea anchor over any prior models is the concurrence of two special characteristics; a very low resistance to acceleration and a very high resistance to high speed while maintaining its hydraulic stability. The result is a very controlled low speed in which the controlled vessel is subject to the least strain from the wind, waves or the sea anchor itself.
Although the sea anchor has been described as being made up from straps, it should be borne in mind that the invention contemplates that orifices can be placed and controllably sized in the side of the surEace of the truncated cone oE the improved sea anchor as is desired for the sea conditions and vessel intended. Thus, other means of construction may be used to obtain the orifices between the strong surface sections of the sea anchor without departing from the spirit of the invention.
Moreover, it will be evident to those skilled in the art that changes in details of construction without departing from the principles of the invention.
12 of 14 `~,
Claims (5)
1. A new sea anchor for a vessel of a generally symmetrical geometric configuration as a hollow and truncated three dimensional body in which there is a base having a greater major transverse dimension than the transverse dimension of the truncated peak thereof and with an outer surface slanting inwardly from the base perimeter at an acute angle and having:
(a) a wide mouth bottom with a strength member at the perimeter of the body base, said member being of a generally uniform weight throughout its perimeter, (b) a strong material forming said outer surface of and said hollow generally truncated body attached to said wide mouth strength member and having orificial openings through said material to cause energy dissipation by the increased velocity thereof, said orificial openings being uniformly distributed throughout said outer surface between said base and peak, (c) the area of said orificed openings being not greater than 75 percent of the surface area of said truncated body, (d) the ratio of the major transverse dimension of the base of the truncated body to the height being in the range of 80 to 90 percent, (e) a bridal means attached to said wide mouth strength member arranged to meet at the longitudinal center line of said body and projecting in a direction opposite to said peak for joining to a single anchor line of said vessel with said meeting point being a distance from said strength member in the range of 1.8 to 2 times the diameter of said strength member, and (f) said truncated peak end thereof is a second strength member and has no orifices and the area thereof is in the range of 15 to 25 percent of the projected transverse opening area of the base of said truncated hollow body whereby the anchor, having the dimensional relationships specified, is hydrodynamically stable as it is dragged through the water.
(a) a wide mouth bottom with a strength member at the perimeter of the body base, said member being of a generally uniform weight throughout its perimeter, (b) a strong material forming said outer surface of and said hollow generally truncated body attached to said wide mouth strength member and having orificial openings through said material to cause energy dissipation by the increased velocity thereof, said orificial openings being uniformly distributed throughout said outer surface between said base and peak, (c) the area of said orificed openings being not greater than 75 percent of the surface area of said truncated body, (d) the ratio of the major transverse dimension of the base of the truncated body to the height being in the range of 80 to 90 percent, (e) a bridal means attached to said wide mouth strength member arranged to meet at the longitudinal center line of said body and projecting in a direction opposite to said peak for joining to a single anchor line of said vessel with said meeting point being a distance from said strength member in the range of 1.8 to 2 times the diameter of said strength member, and (f) said truncated peak end thereof is a second strength member and has no orifices and the area thereof is in the range of 15 to 25 percent of the projected transverse opening area of the base of said truncated hollow body whereby the anchor, having the dimensional relationships specified, is hydrodynamically stable as it is dragged through the water.
2. A sea anchor according to Claim 1 in which the truncated cone volume is in proportion to the displacement of the vessel for which it is intended and is about 2600 pounds per cubic foot.
3. A sea anchor according to Claim 1 in which said strong material forming said hollow truncated cone comprises:
(a) a multiplicity of circumferentially uniformly spaced longitudinal strength webs attached to and extending between said strength members, and (b) a number of substantially uniformly spaced longitudinally spaced webs arranged transverse to attach said longitudinal webs to form a grid so that said orificial openings are general rectangular.
(a) a multiplicity of circumferentially uniformly spaced longitudinal strength webs attached to and extending between said strength members, and (b) a number of substantially uniformly spaced longitudinally spaced webs arranged transverse to attach said longitudinal webs to form a grid so that said orificial openings are general rectangular.
4. A sea anchor according to Claim 3 in which each of said webs are of a strap-like configuration with their broad faces lying in the plane of the surface of said cone to create broad resistance bands to movement of the anchor through the water.
5. A sea anchor according to Claim 3 or Claim 4 in which the ratio of longitudinal to circumferential web is in the range of 1:2:1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/734,460 | 1985-05-15 | ||
| US06/734,460 US4632051A (en) | 1985-05-15 | 1985-05-15 | Sea anchor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1278958C true CA1278958C (en) | 1991-01-15 |
Family
ID=24951781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000509065A Expired - Lifetime CA1278958C (en) | 1985-05-15 | 1986-05-13 | Sea anchor |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4632051A (en) |
| EP (1) | EP0202860B1 (en) |
| AU (1) | AU581313B2 (en) |
| CA (1) | CA1278958C (en) |
| DE (1) | DE3666566D1 (en) |
| DK (1) | DK223986A (en) |
| NO (1) | NO170757C (en) |
| NZ (1) | NZ216170A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR890700512A (en) * | 1987-02-17 | 1989-04-25 | 존 에번에씨 윌리엄 | Seeker |
| US4926780A (en) * | 1989-01-18 | 1990-05-22 | Wiehagen Fred A | Sea anchor deployment and storage device and associated method |
| US4922847A (en) * | 1989-05-08 | 1990-05-08 | Ryder Jr R James | Pliant anchoring device for use with disposable ballast |
| US5062379A (en) * | 1989-11-27 | 1991-11-05 | Cherry Phillip D | Method and apparatus for controlling the speed of boats |
| US5241922A (en) * | 1991-11-07 | 1993-09-07 | Allen Susie M | Collapsible sea anchor |
| US5419275A (en) * | 1992-12-02 | 1995-05-30 | Wood; Greg H. | Batten reinforced anchoring bag |
| US5317985A (en) * | 1993-02-23 | 1994-06-07 | Shewmon Daniel C | Self-opening belt-like drogues |
| US6154915A (en) * | 1998-09-21 | 2000-12-05 | Wiseman, Jr.; Orville A. | Swimming pool aid |
| US6550413B2 (en) | 2000-12-15 | 2003-04-22 | Jenero Fiorentino | Stabilizer ring for a sea anchor |
| DE10149025C1 (en) * | 2001-09-30 | 2003-04-24 | Stiftung A Wegener Inst Polar | Sea anchor, for moving buoy as result of subsurface currents, comprises open mesh cylinder forming local flow boundary layer |
| US7207287B2 (en) * | 2005-03-15 | 2007-04-24 | Lindy-Little Joe, Inc. | Boat control device |
| US8082868B1 (en) * | 2009-02-06 | 2011-12-27 | Johnson Alford R | Watercraft mooring device |
| US20100263582A1 (en) * | 2009-04-20 | 2010-10-21 | Shelley Jeanne Wier | Harness that holds an appropriate size rock to be used as a backup anchor or stabilization tool |
| US8813671B2 (en) * | 2011-12-14 | 2014-08-26 | The United States Of America As Represented By The Secretary Of The Navy | Water parachute for surface vessel motion impedance |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US300764A (en) * | 1884-06-24 | Adjustable marine drag | ||
| US2100231A (en) * | 1934-06-19 | 1937-11-23 | Edward R Armstrong | Sea bottom anchor system and method of placing the same |
| US2466692A (en) * | 1945-07-31 | 1949-04-12 | Valdemar C Farrell | Sea anchor |
| US2818042A (en) * | 1955-08-29 | 1957-12-31 | Charles E Manhart | Sea anchor |
| US2861534A (en) * | 1955-10-04 | 1958-11-25 | Leo F Fehlner | Sea anchor |
| FR1467877A (en) * | 1965-12-20 | 1967-02-03 | Sea anchor model | |
| US3973236A (en) * | 1974-12-23 | 1976-08-03 | Lockheed Missiles & Space Company, Inc. | Horizontal hydrophone array |
| FR2403929A1 (en) * | 1977-09-26 | 1979-04-20 | Iceberg Transport Int | FLOATING ANCHOR FOR EXERCISING TENSILE EFFORTS |
| GB2115362B (en) * | 1982-02-26 | 1985-07-10 | Btr Plc | Sea anchor |
-
1985
- 1985-05-15 US US06/734,460 patent/US4632051A/en not_active Expired - Lifetime
-
1986
- 1986-05-13 CA CA000509065A patent/CA1278958C/en not_active Expired - Lifetime
- 1986-05-14 AU AU57435/86A patent/AU581313B2/en not_active Ceased
- 1986-05-14 NZ NZ216170A patent/NZ216170A/en unknown
- 1986-05-14 EP EP86303671A patent/EP0202860B1/en not_active Expired
- 1986-05-14 DK DK223986A patent/DK223986A/en not_active Application Discontinuation
- 1986-05-14 NO NO861920A patent/NO170757C/en unknown
- 1986-05-14 DE DE8686303671T patent/DE3666566D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0202860B1 (en) | 1989-10-25 |
| NO861920L (en) | 1986-11-17 |
| DK223986A (en) | 1986-11-16 |
| AU581313B2 (en) | 1989-02-16 |
| US4632051A (en) | 1986-12-30 |
| DK223986D0 (en) | 1986-05-14 |
| NZ216170A (en) | 1988-03-30 |
| DE3666566D1 (en) | 1989-11-30 |
| NO170757C (en) | 1992-12-02 |
| EP0202860A1 (en) | 1986-11-26 |
| NO170757B (en) | 1992-08-24 |
| AU5743586A (en) | 1986-11-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |